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The Engines


Fast Facts

General Electric: 57% marketshare
GE90: 74B - 115B
(74k - 115k lb thrust)

GE9X: ~100k

Rolls-Royce: 25%
Trent800: 875 - 895
(75k - 95k)

Pratt & Whitney: 17%
PW4000 112": 4074 - 4098
(74k - 98k)

The selection of engines for the Boeing 777

All three (General Electric, Rolls-Royce and Pratt&Whitney) major engine companies have an engine-family for the T7.
General Electric has a completely new-developed engine, the GE90.
Pratt & Whitney (PW4000 - 112”) and Rolls Royce (Trent 800) have broadened an existing engine family, so it became suitable for the 777.
The market share of these 3 companies was at the beginning with slight advantages by P&W an RR. But further down the life of the 777 GE makes up this gap and is now the marketleader, perhaps the exclusivity deal with Boeing for the Longer Range 777s (772LR and 773ER) has something to do with this. But nonetheless each family of engines had its own teething problems.

R-R P&W GE
Above you can clearly see how each of the engine makers paints the engine-spinner-cone.
Please click onto the images for further information!


To get a T7 airborne, it requires more powerful engines than ever before. The thrustrange was specified between 74.500 and 90.000 lb - exceeding the then existing enginepower by more than 20.000 pounds.
While the 777 was getting more and more popular with the airlines also the power of the engines grew. Thus, the available engines for the 777 are now having a thrustrange from 74.000 up to 115.000 lb. The 777 is purposely overpowered like most other airplanes, because the 777 has to become airborne in the event that only ONE engine is operating.

Compare the power of the 777 engines: all 4 engines of a 707 produce less power than a single 777 engine.
Compare the size of a T7-engine: you can slide the fuselage of a 737 into the engine inlet of a GE90.


How it works
The huge fan sucks in more than 2 million cubic feet of air per minute while running on take-off power. This airstream is separated into two airflows behind the fan stage. One stream, the larger, flows around the engine core, therefore the 777 engines are called high-bypass engine. The GE90 has a bypass ratio of 9:1, that means every single part of air has 9 companions flowing around the core. The bypass air gets accelerated by the fan and provides a significant share of the thrust, around 90%. Another advantage of the huge amount of bypass air is that the cooler air surrounds the hot engine and the very hot exhaust air thus leading to a reduced noise formation and making the 777 engines much quieter than previous jet engines. The smaller part of the airflow runs through the engine core. There it is running through several compressprs, which are boosting the pressure of it (up to 30 times higher), after being so much compressed it enters the combustor where it gets injected with vapo- rized kerosene and ignited. This mixture expands rapidly and by exiting the combustor it pass through the High Pressure and Low Pressure Turbines which are turning the shaft for the Compressors and the Fan. the 777 engines contains of the Fan, a Low Pressure Compressor, a High Pressure Compressor, the Combustor, a High Pressure Turbine and a Low Pressure Turbine.

Engine Testing
The testing programs were very hard and they were done under new FAA standards. The test engines had to run several thousands of hours on testrigs, being stressed very hard. They had to endure a blade-out test, hereby a fan blade gets severed from the disc by a little explosion bolt, while running. This is proposed to show that the engine casing is strong enough to contain the fragments and the engine can run long enough with reduced power until being shut-down safely. Also the engines must prove its strength during tests, were a flock of birds - simulated by 4 frequently fired bird carcasses - was fired into the inlet and still producing 75% of power and respond to throttles for up to 20 minutes after ingestion. Also a test where a large bird (4 kilos) was fired into the fan at more than 300 km/h to prove the engines suffer no uncontained damage and run for another 20sec until being shut-down by the pilots. The ETOPS-testing contained of 3.000 cycles on ground testing (3 - 4 years of airline service) and they must’ve been tested during 180min single operation at full power to simulate an ETOPS 180 divertion, afterwards the engines must flew 1.000 cycles onboard a 777 to demonstrate its readiness on the plane. In 2002 Boeing, Rolls Royce and some other companies founded the Quiet Technology Demonstrator Cooperation. This Group was to search facts for reducing the noise made by engines. In the 1st stage they reduced the noise at the engine inlet by doing some changes in used materials. In 2005 the 2nd such Group was founded this time with General Electric. An GE90-115B powered 773ER of All Nippon 773ER was used as the testbed. The right mounted GE90 gets ‘smart’ chevrons on the primary and secondary exhaust nozzles. The chevrons on the primary nozzle are symmetric and on the secondary they are asymmetric shaped. This chevrons are made of Nitinol (nickel titanium Naval Ordnance Lab), a shape-memory metal that bends itself into the airflow and though reducing nois on t/o and landing. At high temperatures they bend inwards and while the 777 is in cruise they get cooled by the air and so getting streamlined. Also the engine inlet was modified by adding an in-built noise-reducing treatment and an inlet liner. For testing the noise an airfield in Montana has been modified with a large phased-array-field, more than 600 microphones gathering the sounds. During QTD1 the group discovered an intense tone, peaking at 95dB, some anti-icing exhausts. This was solved by altering the holes to slots.s
 
General Electric GE90 / top
Timeline
  • Program launch:
  • 1st built: 04/93
  • 1st flight:
  • Certification: 11/94
  • ETOPS Approval:
  • EIS: 05/1996 on a BA 777
  • Record thrust: 127.9k lb in 3q/2002 -115B
ge90
All rights reserved, JMO
Technical Factsheet
  • Thrust range: 74k - 115k lbs
  • Fandiameter: 123”
  • Length: 285”
  • Bypass ratio: 9:1
  • Overall pressure ratio: 40:1
  • Stages: F/ 4LPC/ 9HPC/ 6LPT/ 2HPT
Variants:
76B, 85B, 90B, 92B, 94B, 110B, 115B

for T7-models:
777, 77E, 77L, 77F, 77W
The GE90 family is the only all-new engine design for the 777. It was a huge game and GE find out not with few problems. But GE thought that a all-new engine has the best growth potential and a tech- nological edge for powering future planes. In early 1990 GE announced the program and by November 1992 the testing of the engine’s core was underway, by early 1993 the full scale engine begins with testing. The GE90 was the 1st new design for GE since 20 years. But it was the chance for GE to test new materials and technologies, so the GE90 has composite wide-chord blades, a new combustor design and a new HPC. GE was joined by Snecma, France and Fiat Avio, Italy and Ishikawajima-Harima Heavy Industries, Japan to build this new engine family. The main boost for the GE90 was the order from British Airways, a former loyal RR customer, for up to 30 777s. BA later became the launch customer of the GE90 powered 777. The GE90 is the world’s largest and most powerful engine. The highest bypass ratio (9:1) makes the GE90 also the quietest of the 777 engines. The GE90 is also a two-spool engine, the low pressure shaft has the fan, a three-stage LPC and a six-stage LPT. The High Pressure Shaft has a 10-stage HPC and a tow-stage HPT. The composite blades also have a not so severe impact if a blade separates. The leading edges are strengthened by titanium for a better protection against foreign object damage. The GE90 comb- ustor is a new dual-dome design, which has two burner zones arranged in a ring around the engine. For lower power settings, i.e. before take-off only the pilot burner operates, if more power is needed the main burner joines. This reduces emissions, especially hydrocarbons and carbon monoxide. Two major incidents halted the test pro- gram, an inflight surge and a bad birdstrike test. The -115B and the -110B both have an additional LPC stage, while the exhaust gas temperatur is being significant reduced. Also this two powerful engines have swept wide-chord blades.
Snecma (.fr), Avio (.it) and IHI (.jp) also participate in the development of the GE90.
Rolls-Royce Trent800 (fan: 110") / top
Timeline
  • Program launch: late 1980s
  • 1st built: 08/1993
  • 1st flight: 2/2/1995
  • Certification: 01/1995
  • ETOPS Approval: 10/1996
  • EIS: 08/1996 on a CX 777
trent_cutaway
© Image is courtesy of Rolls-Royce plc
Technical Factsheet
  • Thrust range: 75k - 95k lbs
  • Fandiameter: 110”
  • Length: 280”
  • Bypass ratio: 6:4
  • Stages: F/ 8IPC/ 6HPC/ 1HPT/ 1IPT/ 5LPT
Variants:
875, 877, 884, 892, 895

for T7-models:
777, 77E, 773
Rolls Royce opted to further develop an existing engine family - the Trent series. RR Engineers started with the Trent800 program in the late 1980s for a thrust range between 75.000 and 95.000 lbs, but with an increased range on option.The main difference is again the increased enginediameter (110” to 86”). RR left the previous operating parameters close to the Trents already in service. The 800 only operates at a 100° increased temperature. Main difference between the Trent and the other 777 engines is that the 800 is a three-spool design. Therefore reducing the needed compression and turbine stages. Allowing also a shorter engine. Trent’s extra spool is an intermediate pressure shaft which conencts an eight-stage IPC with a single- stage turbine. The high pressure spool has a six-stage HPC and a single-stage HPT. A five-stage LPT is driving the fan. 26 wide-chord blades build the fan, pioneerd by the RR engine for the 757. They are aerodynamically more efficient and provide more thrust (cleaner airflow). The blades are built of hollow titanium. The Trent is also the lightest 777 engine. During testing it was discovered that the rear part of the engine produces a stong enough vibration to crack up some rear parts of the engine, material changes extinguished this problem.
Pratt & Whitney PW4000 (fan: 112") / top
Timeline
  • Program launch: 10/1990
  • 1st built: 1/7/1992
  • 1st flight: 9/11/93
  • Certification: 04/1994
  • ETOPS Approval: 04/1994
  • EIS: May 1995
pw_cut
© Image is courtesy of Pratt & Whitney
Technical Factsheet
  • Thrust range: 74k - 98k lbs
  • Fandiameter: 112”
  • Length: 280”
  • Bypass ratio: 6:4
  • overall press. ratio: 34.2 - 42.8
Variants:
4074, 4077(D), 4084(D), 4090, 4098

for T7-models:
777, 77E, 773
The PW4000-112" was the launch engine for the 777. This engine was derived from the 4000-110" family, which already was powering 747s and 767s. The program started in the 4th quarter of 1989. PW choosed to build on the 4000 family because of service readiness and reliability by previous engines. Its main difference to former 4000’s is the 112” large fan, being 18” larger than the engines for the 747.
The PW 777 engines have 22 wide-chord fan blades, an 11-stage HPC, a combustor and a two-stage HPT. The LPC has six-stages ad the LPT is seven-staged. 22 PW4000 were occupied for the test program. After a long period of ground testing, Boeing’s engineers wanted the 1st PW4000 to be tested in the air. So they modified the 1st build 747 to accomo- date the large engine. This tests had its climax in an enginesurge during a take-off, where a false airflow in the engine was leading to a engine flame out. Afterwards PW changed some things in the engine, to better cope with some problems.

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